Roll src/third_party/skia a19abd58cb38..af564a5d0b8b (4 commits)

https://skia.googlesource.com/skia.git/+log/a19abd58cb38..af564a5d0b8b

git log a19abd58cb38..af564a5d0b8b --date=short --first-parent --format='%ad %ae %s'
2020-04-17 senorblanco@chromium.org Dawn: implement fences, callbacks and Finish (syncGpu) semantics.
2020-04-17 mtklein@google.com test overdraw filter via public api
2020-04-17 bsalomon@google.com Fix two GrProcessor names that are not valid idenitfiers
2020-04-17 robertphillips@google.com Update DDL test harness to use backendTextures to back tiles (take 2)

Created with:
  gclient setdep -r src/third_party/skia@af564a5d0b8b

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/skia-autoroll
Please CC kjlubick@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux-blink-rel;luci.chromium.try:linux-chromeos-compile-dbg;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Bug: chromium:1056730
Tbr: kjlubick@google.com
Change-Id: I46f2e1875f89078afbd22a9f7611dc6f2c5a483b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2154887
Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#760124}

DEPS

@@ -175,7 +175,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling Skia
   # and whatever else without interference from each other.
-  'skia_revision': 'a19abd58cb382099ecb977f3e232cae1e4b1328e',
+  'skia_revision': 'af564a5d0b8b8dd5be8a1e3a52d769c431fa9563',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.